U.S. patent number 10,722,214 [Application Number 15/850,799] was granted by the patent office on 2020-07-28 for ultrasonic device, ultrasonic probe, and ultrasonic apparatus.
This patent grant is currently assigned to Seiko Epson Corporation. The grantee listed for this patent is Seiko Epson Corporation. Invention is credited to Chikara Kojima, Eiji Osawa.
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United States Patent |
10,722,214 |
Osawa , et al. |
July 28, 2020 |
Ultrasonic device, ultrasonic probe, and ultrasonic apparatus
Abstract
An ultrasonic device includes a substrate that is provided with
an opening and a partition wall surrounding the opening, a
vibration portion that closes one end side of the opening, and a
piezoelectric element that is provided in the vibration portion, in
which, in a case where an opening width dimension of the opening is
indicated by W, and a thickness dimension of the substrate is
indicated by H, a ratio W/H is 0.66 to 0.92.
Inventors: |
Osawa; Eiji (Suwa,
JP), Kojima; Chikara (Matsumoto, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Seiko Epson Corporation |
Tokyo |
N/A |
JP |
|
|
Assignee: |
Seiko Epson Corporation
(JP)
|
Family
ID: |
62782038 |
Appl.
No.: |
15/850,799 |
Filed: |
December 21, 2017 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20180192995 A1 |
Jul 12, 2018 |
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Foreign Application Priority Data
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|
|
|
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Jan 6, 2017 [JP] |
|
|
2017-000917 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B06B
1/0622 (20130101); A61B 8/4494 (20130101); A61B
8/15 (20130101); A61B 8/08 (20130101); A61B
8/0833 (20130101); A61B 8/56 (20130101); A61B
5/0035 (20130101); A61B 8/4444 (20130101); G01N
2291/106 (20130101); A61B 8/13 (20130101) |
Current International
Class: |
B06B
1/06 (20060101); A61B 8/00 (20060101); A61B
8/15 (20060101); A61B 5/00 (20060101); A61B
8/08 (20060101); A61B 8/13 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
|
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2010-164331 |
|
Jul 2010 |
|
JP |
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2011-259274 |
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Dec 2011 |
|
JP |
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2013-539254 |
|
Oct 2013 |
|
JP |
|
2016-019012 |
|
Feb 2016 |
|
JP |
|
2016-181842 |
|
Oct 2016 |
|
JP |
|
Primary Examiner: Martin; J. San
Attorney, Agent or Firm: Harness, Dickey & Pierce,
P.L.C.
Claims
What is claimed is:
1. An ultrasonic device comprising: a substrate having a through
hole and a partition wall, the partition wall surrounding the
through hole, the through hole having first and second openings
opposite to each other; a vibration plate having first and second
surfaces opposite to each other, the first surface of the vibration
plate closing the first opening of the through hole; a
piezoelectric element that is provided on the second surface of the
vibration plate; an acoustic layer filled into the through hole;
and an acoustic lens disposed on the substrate, the acoustic lens
contacting an end of the partition wall located next to the second
opening, wherein the ultrasonic device is configured to transmit an
ultrasonic wave toward a target object, and the ultrasonic device
is configured to receive a reflected ultrasonic wave that is formed
by reflecting the ultrasonic wave off of the target object and to
output a received signal corresponding to a received voltage, and
wherein, where when an opening width dimension of the first opening
is indicated by W, a thickness dimension of the substrate is
indicated by H, and a ratio W/H is 0.66 to 0.92, a normalized value
of the received voltage is in a range of 0.8 to 1.0.
2. An ultrasonic device comprising: a substrate having a through
hole and a partition wall, the partition wall surrounding the
through hole, the through hole having first and second openings
opposite to each other; a support film having first and second
surfaces opposite to each other, a vibration portion of the first
surface closing the first opening of the through hole; a beam
having first and second ends, the first end being fixed to a first
position of the second surface of the support film, the partition
wall and the beam being overlapped each other at the first positon
in a plan view; a piezoelectric element that is provided on a
second position of the second surface of the support film, the
second positon of the second surface corresponding to the vibration
portion of the first surface of the support film; an acoustic layer
filled into the through hole; and an acoustic lens disposed on the
substrate, the acoustic lens contacting an end of the partition
wall located next to the second opening, wherein the ultrasonic
device is configured to transmit an ultrasonic wave toward a target
object, and the ultrasonic device is configured to receive a
reflected ultrasonic wave that is formed by reflecting the
ultrasonic wave off of the target object and to output a received
signal corresponding to a received voltage, and wherein, when a
width dimension of the vibration portion is indicated by S, a
thickness dimension of the substrate is indicated by H, and a ratio
S/H is 0.73 to 1.16, a normalized value of the received voltage is
in a range of 0.8 to 1.0.
3. An ultrasonic probe comprising: the ultrasonic device according
to claim 1; and a casing in which the ultrasonic device is
stored.
4. An ultrasonic probe comprising: the ultrasonic device according
to claim 2; and a casing in which the ultrasonic device is
stored.
5. An ultrasonic apparatus comprising: the ultrasonic device
according to claim 1; and a controller that controls the ultrasonic
device.
6. An ultrasonic apparatus comprising: the ultrasonic device
according to claim 2; and a controller that controls the ultrasonic
device.
Description
BACKGROUND
1. Technical Field
The present invention relates to an ultrasonic device, an
ultrasonic probe, and an ultrasonic apparatus.
2. Related Art
In the related art, there is an ultrasonic device in which a
support film closing openings is provided on one surface side of a
substrate having the openings, and piezoelectric elements are
provided on the support film at positions overlapping the openings
(for example, refer to JP-A-2010-164331 and JP-A-2013-539254).
In the ultrasonic device disclosed in JP-A-2010-164331 or
JP-A-2013-539254, a partition wall (substrate) is provided to
surround the openings, the support film is caused to vibrate by
using the piezoelectric elements, and thus ultrasonic waves are
output toward the partition wall side of the openings.
Here, in the ultrasonic device disclosed in JP-A-2010-164331, an
opening width of the opening is about 100 .mu.m to about several
hundreds of .mu.m, and a height of the partition wall (a depth of
the opening) is about 100 .mu.m. In the ultrasonic device disclosed
in JP-A-2013-539254, an opening width of the opening is 802 .mu.m,
and a height of the partition wall is 3 mm (3000 .mu.m).
Meanwhile, in an ultrasonic device having such a configuration, a
relationship between an opening width of an opening and a height of
a partition wall of the opening (a thickness dimension of a
substrate) is an important parameter in performing ultrasonic
measurement at high transmission/reception sensitivity.
However, in the above-described ultrasonic device disclosed in
JP-A-2010-164331 or JP-A-2013-539254, a relationship between an
opening width and a height of a partition wall is not taken into
consideration, and sufficient transmission/reception
characteristics cannot be obtained.
SUMMARY
An advantage of some aspects of the invention is to provide an
ultrasonic device, an ultrasonic probe, and an ultrasonic apparatus
having high transmission/reception sensitivity, and, application
examples and embodiments thereof will now be described.
An ultrasonic device according to an application example of the
invention includes a substrate that is provided with an opening and
a partition wall surrounding the opening; a vibration portion that
closes one end side of the opening; and a piezoelectric element
that is provided in the vibration portion, in which, in a case
where an opening width dimension of the opening is indicated by W,
and a thickness dimension of the substrate is indicated by H, a
ratio W/H is 0.66 to 0.92.
In this application example, the opening is formed by the partition
wall surrounding four sides, and the vibration portion is disposed
on one end side of the opening. In this ultrasonic device, the
vibration portion vibrates when the piezoelectric element is
driven, and thus an ultrasonic wave is transmitted. The vibration
portion is caused to vibrate due to an ultrasonic wave, and thus a
signal is output from the piezoelectric element such that reception
of the ultrasonic wave is detected.
Meanwhile, as a result of intensive studies, the present inventor
of the present specification has obtained the findings that the
transmission/reception sensitivity is changed by the opening width
dimension W of the opening and the thickness dimension (a height
dimension of the partition wall) H of the substrate, and an
ultrasonic device having high transmission/reception sensitivity
can be implemented by appropriately setting the opening width
dimension W and the thickness dimension H.
In other words, in this application example, the ratio (W/H)
between the opening width dimension W of the opening and the
thickness dimension H of the substrate is 0.66 to 0.92. In the
ultrasonic device, it is possible to increase the reception
sensitivity of when an ultrasonic wave (reflected wave) reflected
from a subject is received after an ultrasonic wave is transmitted
during transmission of the ultrasonic wave. In other words, it is
possible to increase the transmission/reception sensitivity in the
ultrasonic device.
An ultrasonic device according to an application example of the
invention includes a substrate that is provided with an opening and
a partition wall surrounding the opening; a support film that
closes one end side of the opening, and has a first surface facing
the opening and a second surface which is a rear surface of the
first surface; a beam portion that joins a sealing plate disposed
on the second surface side of the support film to the second
surface of the support film; and a piezoelectric element that is
provided on the support film, in which the support film includes a
vibration portion surrounded by an edge of the partition wall and
an edge of the beam portion in a plan view from a thickness
direction of the substrate, in which the piezoelectric element is
provided in the vibration portion, and, in which, in a case where a
width dimension of the vibration portion is indicated by S, and a
thickness dimension of the substrate is indicated by H, a ratio S/H
is 0.73 to 1.16.
In this application example, the sealing plate is disposed on the
substrate on the support film side, and the support film is joined
to the sealing plate via the beam portion. In the application
example, in the support film closing the opening, for example, a
region surrounded by edges of a pair of partition walls facing each
other in a plan view and edges of a pair of beam portions facing
each other, or a region of which three sides are surrounded by
edges of the partition walls and an edge of the beam portion is
disposed at one remaining side serves as the vibration portion.
In this application example, the ratio (S/H) between the width
dimension S of the vibration portion and the thickness dimension H
of the substrate is 0.73 to 1.16. In the ultrasonic device, it is
possible to increase the reception sensitivity of when an
ultrasonic wave (reflected wave) reflected from a subject is
received after an ultrasonic wave is transmitted during
transmission of the ultrasonic wave. In other words, it is possible
to increase the transmission/reception sensitivity in the
ultrasonic device.
An ultrasonic probe according to an application example of the
invention includes the ultrasonic device described above; and a
casing in which the ultrasonic device is stored.
In this application example, as described above, the
transmission/reception sensitivity in the ultrasonic device is
high. Therefore, in the ultrasonic probe including such an
ultrasonic device, an ultrasonic measurement process can be
performed with high accuracy when ultrasonic measurement is
performed, and thus it is possible to obtain a highly accurate
measurement result.
An ultrasonic apparatus according to an application example of the
invention includes the ultrasonic device described above; and a
controller that controls the ultrasonic device.
In this application example, as described above, the
transmission/reception sensitivity in the ultrasonic device is
high. Therefore, in the ultrasonic apparatus, the controller
controls the ultrasonic device, and thus it is possible to perform
a transmission process or a reception process of an ultrasonic wave
with high accuracy.
Consequently, it is possible to perform various ultrasonic
processes such as ultrasonic measurement on a subject or ultrasonic
therapy on a subject with high accuracy.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described with reference to the accompanying
drawings, wherein like numbers reference like elements.
FIG. 1 is a perspective view illustrating a schematic configuration
of an ultrasonic measurement apparatus according to a first
embodiment.
FIG. 2 is a sectional view illustrating a schematic configuration
of an ultrasonic probe according to the first embodiment.
FIG. 3 is a schematic plan view of an ultrasonic device according
to the first embodiment.
FIG. 4 is a sectional view of the ultrasonic device taken along the
line A-A in FIG. 3.
FIG. 5 is a diagram illustrating a received voltage which is output
when an ultrasonic wave is received by an ultrasonic transducer at
a ratio between an opening width dimension of an opening and a
height dimension of a partition wall in the first embodiment.
FIG. 6 is a schematic plan view of an ultrasonic device according
to a second embodiment.
FIG. 7 is a sectional perspective view illustrating a schematic
configuration of the ultrasonic device according to the second
embodiment.
FIG. 8 is a diagram illustrating a received voltage which is output
when an ultrasonic wave is received by an ultrasonic transducer at
a ratio between a width dimension and a height dimension of a
partition wall of a vibration portion of the second embodiment.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
First Embodiment
Hereinafter, a first embodiment will be described.
FIG. 1 is a perspective view illustrating a schematic configuration
of an ultrasonic measurement apparatus 1 according to the first
embodiment.
The ultrasonic measurement apparatus 1 corresponds to an ultrasonic
apparatus, and includes, as illustrated in FIG. 1, an ultrasonic
probe 2 and a control device 10 connected to the ultrasonic probe 2
via a cable 3.
The ultrasonic measurement apparatus 1 transmits ultrasonic waves
into a subject from the ultrasonic probe 2 in a state in which the
ultrasonic probe 2 is brought into contact with a surface of the
subject (for example, a living body such as a human body). In the
ultrasonic measurement apparatus 1, ultrasonic waves reflected from
an organ in the subject are received by the ultrasonic probe 2,
and, for example, an internal tomographic image of the subject is
obtained or a state (for example, a blood flow) of an organ in the
subject is measured, on the basis of a received signal.
Configuration of Control Device
The control device 10 corresponds to a controller, and includes, as
illustrated in FIG. 1, an operation unit 11 provided with a button
or a touch panel, and a display unit 12. Although not illustrated,
the control device 10 includes a storage unit formed of a memory or
the like, and a calculation unit formed of a central processing
unit (CPU) or the like. The control device 10 causes the
calculation unit to execute various programs stored in the storage
unit, and thus controls the ultrasonic measurement apparatus 1. For
example, the control device 10 outputs a command for controlling
driving of the ultrasonic probe 2, forms an image of an internal
structure of a subject and displays the image on the display unit
12 on the basis of a received signal which is input from the
ultrasonic probe 2, or measures biological information such as a
blood flow and displays the biological information on the display
unit 12. As the control device 10, for example, a terminal device
such as a tablet terminal, a smart phone, or a personal computer
may be used, and a dedicated terminal device for operating the
ultrasonic probe 2 may be used.
Configuration of Ultrasonic Probe
FIG. 2 is a sectional view illustrating a schematic configuration
of the ultrasonic probe 2.
As illustrated in FIG. 2, the ultrasonic probe 2 includes a casing
21, an ultrasonic device 22 stored in the casing 21, and a circuit
substrate 23 provided with a driver circuit and the like for
controlling the ultrasonic device 22. An ultrasonic sensor 24 is
formed of the ultrasonic device 22 and the circuit substrate
23.
Configuration of Casing
As illustrated in FIG. 1, the casing 21 is formed in a rectangular
box shape in a plan view, and is provided with a sensor window 21B
on one surface (sensor surface 21A) which is orthogonal to a
thickness direction, and a part of the ultrasonic device 22 is
exposed to one surface. A passing hole 21C of the cable 3 is
provided at a part (a side surface in the example illustrated in
FIG. 1) of the casing 21. The cable 3 is inserted into the casing
21 through the passing hole 21C so as to be connected to the
circuit substrate 23. A gap between the cable 3 and the passing
hole 21C is filled with, for example, a resin material, and thus
water resistance is ensured.
In the present embodiment, a configuration example in which the
ultrasonic probe 2 is connected to the control device 10 via the
cable 3 is described, but this is only an example, and, for
example, the ultrasonic probe 2 and the control device 10 may be
connected to each other via wireless communication, and various
constituent elements of the control device 10 may be provided in
the ultrasonic probe 2.
Configuration of Circuit Substrate
The circuit substrate 23 is electrically connected to a drive
terminal 431A and a common terminal 433B (refer to FIG. 3) of the
ultrasonic device 22 which will be described later, and controls
the ultrasonic device 22 under the control of the control device
10.
Specifically, the circuit substrate 23 is provided with a
transmission circuit, a reception circuit, and the like. The
transmission circuit outputs a drive signal for causing the
ultrasonic device 22 to transmit an ultrasonic wave. The reception
circuit acquires a received signal output from the ultrasonic
device 22 having received an ultrasonic wave, performs an
amplification process, an A/D conversion process, a phasing
addition process, and the like on the received signal, and outputs
the received signal having undergone the processes to the control
device 10.
Configuration of Ultrasonic Device
FIG. 3 is a plan view of the ultrasonic device 22. In FIG. 3, a
sealing plate 44 (refer to FIG. 4) and an acoustic member 45 (refer
to FIG. 4) are not illustrated.
As illustrated in FIG. 3, in the ultrasonic device 22, a plurality
of ultrasonic transducers 50 are disposed in a two-dimensional
array form along an X direction (scanning direction) and a Y
direction (slice direction) intersecting (in the present
embodiment, as an example, orthogonal to) each other. In the
present embodiment, a transmission/reception row Ch (electrode
group) of one channel (CH) is formed of a plurality of ultrasonic
transducers 50 disposed in the Y direction. The
transmission/reception row Ch of one CH is arranged in a plurality
along the Y direction such that the ultrasonic device 22 of a
one-dimensional array structure is configured. Here, a region in
which the ultrasonic transducers 50 are disposed is referred to as
an array region Ar.
For convenience of description, in FIG. 3, the number of disposed
ultrasonic transducers 50 is reduced, but, actually, more
ultrasonic transducers 50 are disposed.
FIG. 4 is a sectional view of the ultrasonic device 22 taken along
the line A-A in FIG. 3.
As illustrated in FIG. 4, the ultrasonic device 22 is configured to
include an element substrate 41, a support film 42, a piezoelectric
element 43, a sealing plate 44, and an acoustic member 45.
Configuration of Element Substrate 41
The element substrate 41 is formed of, for example, a semiconductor
substrate such as Si. The element substrate is provided with
openings 41A corresponding to the respective ultrasonic transducers
50. In the present embodiment, each opening 41A is a penetration
hole which penetrates through the element substrate 41 in a
substrate thickness direction, and the support film 42 is provided
on one end side (sealing plate 44 side) of the penetration hole.
Here, a portion of the element substrate 41 joined to the support
film 42 is a partition wall 41B, and the opening 41A is formed as a
result of being surrounded by the partition walls 41B on four sides
(.+-.X sides and .+-.Y sides). In other words, the partition walls
41B located on the .+-.X sides of the opening 41A face each other
with the opening 41A interposed therebetween, and the partition
walls 41B located on the .+-.Y sides of the opening 41A face each
other with the opening 41A interposed therebetween. Here, in the
present embodiment, regarding an opening width dimension of the
opening 41A, a width dimension of the opening 41A in the Y
direction is larger than a width dimension thereof in the X
direction, and thus the opening 41A has a rectangular shape.
Configuration of Support Film 42
The support film 42 is formed of, for example, a laminate of
SiO.sub.2 and ZrO.sub.2, and is provided to cover the entire
element substrate 41 on the sealing plate 44 side. In other words,
the support film 42 is supported by the partition walls 41B forming
the opening 41A, and closes the opening 41A on the sealing plate 44
side. A thickness dimension of the support film 42 is sufficiently
smaller than a thickness dimension of the element substrate 41.
Here, a portion of the support film 42 closing the opening 41A
forms a vibration portion 421, and a single ultrasonic transducer
50 is formed of the vibration portion 421 and the piezoelectric
element 43.
The piezoelectric element 43 is provided on each vibration portion
421. The piezoelectric element 43 is formed of, for example, a
laminate obtained by laminating a lower electrode 431, a
piezoelectric film 432, and an upper electrode 433 from the support
film 42 side.
In the ultrasonic transducer 50, a rectangular wave voltage (drive
signal) having a predetermined frequency is applied between the
lower electrode 431 and the upper electrode 433, so that the
piezoelectric film 432 is bent, and thus the vibration portion 421
vibrates such that an ultrasonic wave is sent. If the vibration
portion 421 vibrates due to an ultrasonic wave (reflected wave)
reflected from a subject, a potential difference occurs between
upper and lower parts of the piezoelectric film 432. Consequently,
the potential difference generated between the lower electrode 431
and the upper electrode 433 is detected, and thus a received
ultrasonic wave can be detected.
In the present embodiment, as illustrated in FIG. 3, the lower
electrode 431 is formed linearly along the Y direction, and
connects a plurality of ultrasonic transducers 50 forming the
transmission/reception row Ch of one CH to each other. The drive
terminals 431A are provided at both ends of the lower electrode
431. The drive terminals 431A are electrically connected to the
circuit substrate.
The upper electrode 433 is formed linearly along the X direction,
and connects the ultrasonic transducers 50 arranged in the X
direction to each other. Ends of the upper electrode 433 on the
.+-.Y sides are connected to common electrode lines 433A. The
common electrode line 433A connects a plurality of upper electrodes
433 disposed in the X direction to each other, and is provided with
the common terminals 433B electrically connected to the circuit
substrate at ends thereof.
Configuration of Sealing Plate 44
A planar shape of the sealing plate 44 viewed from the thickness
direction is formed to be the same as, for example, that of the
element substrate 41, and is formed of a semiconductor substrate
such as Si or an insulator substrate. A material or a thickness of
the sealing plate 44 influences frequency characteristics of the
ultrasonic transducer 50, and is thus preferably set on the basis
of a center frequency of an ultrasonic wave which is transmitted
and received in the ultrasonic transducer 50.
The sealing plate 44 is joined to, for example, a portion of the
support film 42 supported at the partition wall 41B via a beam
portion 441 made of a resin member such as a resist. Consequently,
a gap having a predetermined dimension is provided between the
sealing plate 44 and the vibration portion 421 in a region facing
the vibration portion 421, and thus vibration of the vibration
portion 421 is not hindered. Since the beam portion 441 is provided
in the region of the support film 42 supported at the partition
wall 41B, it is possible to prevent the occurrence of a problem
(crosstalk) that a back wave from each ultrasonic transducer 50 is
incident to another ultrasonic transducer 50 adjacent thereto.
The sealing plate 44 is provided with a connection portion which
connects the drive terminals 431A and the common terminals 433B to
the circuit substrate 23 at positions facing the respective
terminals (the drive terminals 431A and the common terminals 433B)
of the element substrate 41. The connection portion may have an
exemplary configuration including, for example, openings provided
in the sealing plate 44, and a wiring member (a flexible printed
circuits (FPC), cables, or wires) connecting the respective
terminals (the drive terminals 431A and the common terminals 433B)
to the circuit substrate 23 via the openings.
Configuration of Acoustic Member 45
The acoustic member 45 is provided on the +Z side of the element
substrate 41, and is configured to include an acoustic layer 451
and an acoustic lens 452.
The acoustic member 45 is preferably made of, for example, a
viscoelastic material or elastomer, and is more preferably made of
silicon rubber or butadiene rubber. Acoustic impedance of the
acoustic member 45 is preferably acoustic impedance (for example,
1.5 MRayls in a case where a subject is a human body) close to
acoustic impedance of a subject. Consequently, the acoustic member
45 causes an ultrasonic wave transmitted from the ultrasonic
transducer 50 to propagate toward a subject with high efficiency,
and causes an ultrasonic wave reflected inside the subject to
propagate toward the ultrasonic transducer 50 with high
efficiency.
The acoustic layer 451 fills each opening 41A on the +Z side of the
element substrate 41. In other words, since the acoustic layer 451
fills the opening 41A, generation of an air bubble or the like is
suppressed between the element substrate 41 and the acoustic layer
451.
As illustrated in FIG. 1, the acoustic lens 452 is exposed to the
outside from a sensor window 21B of a casing 21. In ultrasonic
measurement using the ultrasonic probe 2, the acoustic lens 452
exposed from the casing 21 is brought into contact with a surface
of a subject via an acoustic material such as a gel. The acoustic
lens 452 has a cylindrical shape whose section in a ZX plane is a
circular arc shape, and causes an ultrasonic wave transmitted from
the ultrasonic device 22 to converge at a predetermined depth
position.
Opening Width Dimension of Opening 41A and Height Dimension of
Partition Wall 41B
Next, a description will be made of a relationship between an
opening width dimension of the opening 41A and a height dimension
(a thickness dimension of the element substrate 41) of the
partition wall 41B in the element substrate 41.
FIG. 5 is a diagram illustrating a received voltage which is output
when an ultrasonic wave is received by the ultrasonic transducer 50
at a ratio (W/H) between an opening width dimension W of the
opening 41A and a height dimension (a thickness dimension of the
element substrate 41) H of the partition wall 41B. In FIG. 5, a
received voltage on a longitudinal axis is obtained by normalizing
a value thereof with a case where the received voltage takes the
maximum value as 1.
FIG. 5 illustrates received voltages of when an ultrasonic wave is
transmitted from the ultrasonic transducer 50, and a reflected wave
of the ultrasonic wave reflected from a subject is received.
Therefore, characteristics illustrated in FIG. 5 indicate
characteristics of both of the transmission sensitivity during
transmission of an ultrasonic wave and reception sensitivity during
reception of a reflected wave, that is, transmission/reception
sensitivity of the ultrasonic transducer 50 instead of indicating
the magnitude of a received voltage in a case where an ultrasonic
wave with constant sound pressure is received.
An opening width dimension of the opening 41A is an important
parameter for determining frequencies of ultrasonic waves
transmitted and received in the ultrasonic transducer 50 or the
transmission/reception sensitivity, and the width dimension W of
the opening 41A in a minor axis direction has the great influence
on a frequency in the ultrasonic transducer. In other words, in the
present embodiment, the width dimension (a dimension of the gap
between the partition walls 41B disposed on the .+-.X sides of the
opening 41A) W of the opening 41A in the X direction which is the
minor axis direction has the influence on frequencies of ultrasonic
waves transmitted and received in the ultrasonic transducer 50 and
the transmission/reception sensitivity.
In ultrasonic measurement using the ultrasonic probe 2, an
ultrasonic wave is transmitted from each ultrasonic transducer 50,
and then a reflected wave from a subject is received. The reflected
wave from the subject attenuates in the subject. Here, in a case
where a normalized received voltage is equal to or less than 0.8,
sufficient reception sensitivity cannot be obtained, and
measurement accuracy in the ultrasonic measurement is reduced.
In the present embodiment, the ratio (W/H) between the opening
width dimension W of the opening 41A and the thickness dimension H
of the element substrate 41 is 0.66 to 0.92.
Here, in a case where the ratio (W/H) is less than 0.66, a received
voltage (normalized) of when a reflected wave is received is less
0.8, and thus the transmission/reception sensitivity in the
ultrasonic transducer 50 is reduced. On the other hand, in a case
where the ratio (W/H) exceeds 0.92, as illustrated in FIG. 5, a
value of a received voltage (normalized) rapidly changes. Thus, it
is difficult to maintain stable transmission/reception
sensitivity.
In contrast, as described above, in a case where the ratio (W/H) is
0.66 to 0.92, a value of a received voltage (normalized) is 0.8 to
1.0, so that the transmission/reception sensitivity can be
increased, there is no rapid change in a voltage, and stable
transmission/reception sensitivity can be maintained.
More preferably, the ratio (W/H) between the opening width
dimension W of the opening 41A and the thickness dimension H of the
partition wall 41B is 0.75 to 0.90.
Even in a case where the ratio (W/H) exceeds 0.90, high
transmission/reception sensitivity can be realized up to 0.92, but,
for example, there is a case where the ratio (W/H) exceeds 0.92 due
to a manufacturing error or the like. In this case, as illustrated
in FIG. 5, a received voltage rapidly changes, and, thus, there is
concern that a received voltage is less than 0.8 depending on
cases.
In contrast, in a case where the ratio (W/H) is 0.75 to 0.90, a
normalized received voltage can be stably maintained to be 0.9 or
more, and thus high transmission/reception sensitivity and
reliability of the apparatus can be maintained.
Therefore, in the present embodiment, in a case where the element
substrate 41 of the ultrasonic device 22 is manufactured, first,
the type of subject or a frequency of an ultrasonic wave
corresponding to a measurement depth for the subject is set. Next,
the opening width dimension W of the opening 41A corresponding to
the set frequency is set.
Thereafter, a thickness dimension of the element substrate 41 is
set such that the ratio (W/H) between the opening width dimension W
and the thickness dimension H of the element substrate 41 is 0.66
to 0.92 (preferably, 0.75 to 0.90). In this case, a thickness
dimension of the element substrate 41 is preferably set such that
the ratio (W/H) is 0.90. Here, in a case where it is hard to set
the ratio (W/H) to 0.90 due to, for example, an arrangement space
of the ultrasonic device 22 in the ultrasonic probe 2, or an
arrangement relationship with other constituent components, a
thickness dimension of the element substrate 41 is set such that
the ratio (W/H) is within the range from 0.75 to 0.90. In a case
where it is hard to set the ratio (W/H) to the range, a thickness
dimension of the element substrate 41 is set such that the ratio
(W/H) is within the range from 0.66 to 0.92. Consequently, it is
possible to manufacture the ultrasonic device 22 in which the
transmission/reception sensitivity of an ultrasonic wave is highest
so as to cope with a target measurement depth or a size or the like
of the ultrasonic device 22.
Advantageous Effects of Present Embodiment
The ultrasonic measurement apparatus 1 of the present embodiment
includes the ultrasonic probe 2 and the control device 10, and the
ultrasonic probe 2 includes the casing 21, and the ultrasonic
device 22 stored in the casing 21.
The ultrasonic device 22 includes the element substrate 41 provided
with the opening 41A and the partition wall 41B, the support film
42 closing one end side of the opening 41A, the piezoelectric
element 43 provided on the vibration portion 421 of the support
film 42. The ratio (W/H) between the opening width dimension W of
the opening 41A in the minor axis direction and the thickness
dimension H of the element substrate 41 is 0.66 to 0.92.
In this configuration, as illustrated in FIG. 5, a received voltage
(normalized) of when a reflected wave is received in the ultrasonic
transducer 50 is stabilized and is equal to or more than 0.8. Thus,
it is possible to maintain the transmission/reception sensitivity
in the ultrasonic transducer to be high.
Thus, also in ultrasonic measurement on a living body using the
ultrasonic probe 2, it is possible to appropriately perform
transmission and reception processes of ultrasonic waves with
respect to the living body and thus to realize highly accurate
ultrasonic measurement.
Since highly accurate ultrasonic measurement can be performed by
using the ultrasonic device 22, various processes in the control
device 10 can also be performed with high accuracy. For example, an
internal tomographic image of a living body can be formed with high
accuracy or a blood flow or blood pressure can be measured with
high accuracy on the basis of a result of ultrasonic
measurement.
Second Embodiment
Next, a second embodiment will be described.
In the first embodiment, a description has been made of an example
in which a single ultrasonic transducer 50 is formed of a single
vibration portion 421 closing a single opening 41A, and the
piezoelectric element 43 provided on the vibration portion 421. In
contrast, the second embodiment is different from the first
embodiment in that a plurality of vibration portions are provided
in a single opening, and a piezoelectric element is disposed at
each vibration portion.
In the following description, the constituent elements described
above are given the same reference numerals, and description
thereof will be omitted or made briefly.
FIG. 6 is a plan view of the ultrasonic device 22 of the second
embodiment.
FIG. 7 is a sectional perspective view illustrating a schematic
configuration of the ultrasonic device 22 of the second
embodiment.
As illustrated in FIGS. 6 and 7, in the present embodiment, a
plurality of openings 41C each of which is long in the Y direction
are provided in the X direction on the element substrate 41.
Each opening 41C is a penetration hole which penetrates through the
element substrate 41 in a substrate thickness direction, the
support film 42 is provided on one end side (sealing plate 44 side)
of the penetration hole, and the support film 42 closes one end
side of the opening 41C. In the same manner as in the first
embodiment, the opening 41C is formed as a result of being
surrounded by the partition walls 41B on four sides such as .+-.X
sides and .+-.Y sides. Therefore, the partition walls 41B located
on the .+-.X sides face each other in the X direction, and the
partition walls 41B located on the .+-.Y sides face each other in
the Y direction.
In the same manner as in the first embodiment, the element
substrate 41 is reinforced by the sealing plate 44. The sealing
plate 44 is long in the X direction in at least the array region
Ar, and is joined to the support film 42 via a plurality of beam
portions 442 disposed at equal intervals in the Y direction.
In other words, a first surface of the support film 42 which is a
surface on the element substrate 41 side is joined to the partition
wall 41B, and a second surface (a rear surface of the first
surface) on the sealing plate 44 side is joined to the beam
portions 442.
In this configuration, the support film 42 closing the openings 41C
of the element substrate 41 is divided into a plurality of regions
(vibration portions 422) by edges of the partition walls 41B
forming the openings 41C and edges of the beam portions 442 as
illustrated in FIGS. 6 and 7.
Specifically, the vibration portion 422 is formed as a region
surrounded by an edge of the partition wall 41B extending in the X
direction, two edges of a pair of partition walls 41B extending in
the Y direction and facing each other, and an edge of a single beam
portion 442 extending in the X direction, in the support film 42 at
ends of the opening 41C on the .+-.Y sides. In locations other than
the ends of the opening 41C, the vibration portion 422 is formed as
a region surrounded by two edges of a pair of partition walls 41B
extending in the Y direction and facing each other, and two edges
of a pair of beam portions 442 extending in the X direction and
facing each other in the support film 42.
In the present embodiment, the piezoelectric element 43 is provided
in each vibration portion 422. In other words, in the present
embodiment, the ultrasonic transducer 50 is formed of each
vibration portion 422 and the piezoelectric element 43.
FIG. 8 is a diagram illustrating a received voltage which is output
when an ultrasonic wave is received in the ultrasonic transducer 50
at a ratio (S/H) between a width dimension S of the vibration
portion 422 of the present embodiment and a thickness dimension H
of the element substrate 41. In FIG. 8, in the same manner as in
FIG. 5, a received voltage on a longitudinal axis is obtained by
normalizing a value thereof with a case where the received voltage
takes the maximum value as 1. FIG. 8 illustrates received voltages
of when an ultrasonic wave is transmitted from the ultrasonic
transducer 50, and a reflected wave of the ultrasonic wave
reflected from a subject is received.
Here, the width dimension S of the vibration portion 422 of the
present embodiment is a dimension of a smaller distance of a
distance between the partition walls 41B adjacent to each other and
a distance between the beam portions 442 adjacent to each other. In
the present embodiment, a distance between the partition walls 41B
adjacent to each other is smaller than a distance between the beam
portions 442 adjacent to each other. Therefore, the width dimension
S of the vibration portion 422 is a distance between the partition
walls 41B adjacent to each other.
In the same manner as in the first embodiment, also in the present
embodiment, the width dimension S of the vibration portion 422 and
a thickness dimension (a height dimension of the partition wall
41B) H of the element substrate 41 are set such that a received
voltage (normalized) exceeds 0.8 in ultrasonic measurement using
the ultrasonic probe 2.
In other words, the ratio (S/H) between the width dimension S (a
distance between the partition walls 41B adjacent to each other in
the present embodiment) of the vibration portion 422 and the
thickness dimension H of the element substrate 41 is 0.73 to
1.16.
Here, in cases where the ratio (S/H) is less than 0.73, and exceeds
1.16, a received voltage (normalized) of when a reflected wave is
received is less than 0.8, and thus the transmission/reception
sensitivity in the ultrasonic transducer 50 is reduced.
In contrast, as described above, in a case where the ratio (S/H) is
0.73 to 1.16, a value of a normalized received voltage is 0.8 to
1.0, so that the transmission/reception sensitivity can be
increased, and stable transmission/reception sensitivity can be
realized.
The ratio (S/H) between the width dimension S of the vibration
portion 422 and the thickness dimension H of the element substrate
41 is more preferably within the range from 0.76 to 0.90.
In a case of the above-described ratio (S/H), a received voltage
(normalized) can be stably maintained to be 0.9 or more, and thus
high transmission/reception sensitivity can be maintained. In a
case where the ratio (S/H) is 1.00 to 1.10, a received voltage
(normalized) can be maintained to be 0.9 or more, but there is a
case where a received voltage is reduced to below 0.9 due to a
manufacturing error or the like.
Therefore, in the present embodiment, in a case where the element
substrate 41 of the ultrasonic device 22 is manufactured, first,
the type of subject or a frequency of an ultrasonic wave
corresponding to a measurement depth for the subject is set. Next,
the opening width dimension S (an interval between the partition
walls 41B adjacent to each other) of the opening 41A corresponding
to the frequency is set.
Thereafter, a thickness dimension of the element substrate 41 is
set such that the ratio (S/H) between the opening width dimension S
and the thickness dimension H of the element substrate 41 is 0.73
to 1.16 (preferably, 0.76 to 0.91 or 1.00 to 1.10). In this case, a
thickness dimension of the element substrate 41 is preferably set
such that the ratio (S/H) is 0.86 and thus the reception
sensitivity (normalized) becomes 1. Here, in a case where it is
hard to set the ratio (S/H) to 0.86 due to, for example, an
arrangement space of the ultrasonic device 22 in the ultrasonic
probe 2, or an arrangement relationship with other constituent
components, a thickness dimension of the element substrate 41 is
set such that the ratio (S/H) is within the range from 0.76 to
0.91. In a case where it is hard to set the ratio (S/H) to the
range, a thickness dimension of the element substrate 41 is set
such that the ratio (S/H) is within the range from 1.00 to 1.10. In
a case where it is harder to set the ratio (S/H) to the range, a
thickness dimension of the element substrate 41 is set such that
the ratio (S/H) is within the range from 0.73 to 1.16.
Consequently, it is possible to manufacture the ultrasonic device
22 in which the transmission/reception sensitivity of an ultrasonic
wave is highest so as to cope with a target measurement depth or a
size or the like of the ultrasonic device 22.
Advantageous Effects of Present Embodiment
The ultrasonic device 22 includes the element substrate 41 provided
with the opening 41C and the partition wall 41B, and the support
film 42 closing one end side of the opening 41C. The first surface
of the support film 42 on the element substrate 41 side is joined
to the partition wall 41B, and the surface thereof which is a rear
surface of the first surface on the sealing plate 44 side is joined
to the beam portion 442. The opening 41C is long in the Y
direction, and a plurality of beam portions 442 each of which is
long in the X direction are provided in the Y direction at
positions overlapping the openings 41C in a plan view.
Consequently, in the support film 42, a plurality of vibration
portions 422 surrounded by edges of the partition walls 41B and
edges of the beam portions 442 are obtained, and the piezoelectric
element 43 is provided on the vibration portion 422.
In the present embodiment, the ratio (S/H) between the width
dimension S of the vibration portion 422 in the minor axis
direction and the thickness dimension H of the element substrate 41
is 0.73 to 1.16.
In this configuration, as illustrated in FIG. 8, a received voltage
(normalized) of when a reflected wave is received in the ultrasonic
transducer 50 is stabilized and is equal to or more than 0.8. Thus,
it is possible to maintain the transmission/reception sensitivity
in the ultrasonic transducer to be high.
Modification Examples
The invention is not limited to the above-described embodiments,
and includes configurations obtained through modifications and
alterations within the scope in which the object of the invention
can be achieved, and combinations of the respective
embodiments.
For example, in the second embodiment, a description has been made
of an exemplary configuration in which each opening 41C is long in
the Y direction, but this is only an example. For example, the
opening 41C may be formed to be long in the X direction (scanning
direction). In this case, a plurality of beam portions 442 each of
which is formed to be long in the Y direction are disposed in the X
direction.
In the second embodiment, a description has been made of an example
in which a distance between the partition walls 41B adjacent to
each other is smaller than a distance between the beam portions 442
adjacent to each other, but this is only an example. For example, a
distance between the beam portions 442 adjacent to each other is
smaller than a distance between the partition walls 41B adjacent to
each other. In this case, the width dimension S of the vibration
portion 422 is a distance between the beam portions 442 adjacent to
each other.
In the second embodiment, a description has been made of an
exemplary configuration in which the beam portion 442 is provided
over ends on the .+-.X sides in the array region Ar, but this is
only an example.
In other words, among a plurality of openings 41C provided in the X
direction, the beam portion 442 may straddle a predetermined number
of openings 41C so as to be provided to be long in the X
direction.
For example, the beam portion 442 may be provided from the
partition wall 41B disposed on the -X side of a single opening 41C
to the partition wall 41B disposed on the +X side of the opening
41C. In this case, a plurality of beam portions 442 are provided in
the X direction.
In the second embodiment illustrated in FIG. 6, a description has
been made of an exemplary configuration in which the beam portions
442 are provided in only the array region Ar, but this is only an
example, and a joint member which joins the support film 42 to the
sealing plate 44 outside the array region Ar may be provided.
The joint member may be formed of a resin member such as a resist,
and may be formed in the same process as the beam portions 442. The
joint member may be connected to the beam portions 442 outside the
array region Ar, and may be provided separately from the beam
portions 442. The joint member is preferably provided over the
periphery of the array region Ar in order to improve the joint
strength between the support film 42 and the sealing plate 44.
In the embodiments, as an electronic apparatus, a description has
been made of an exemplary configuration in which the ultrasonic
apparatus employs an organ in a subject as a measurement target,
but the invention is not limited thereto.
For example, the configurations of the embodiments and each
modification example are applicable to a measurement apparatus
which employs various structural bodies as subjects, and detects
defects of the structural bodies or examines deterioration
thereof.
For example, the configurations of the embodiments and each
modification example are applicable to a measurement apparatus
which employs various semiconductor packages, wafers, or the like
as measurement targets, and detects defects of the measurement
targets.
The ultrasonic measurement apparatus performing ultrasonic
measurement on a subject has been exemplified, but is not limited
thereto.
For example, the configurations of the embodiments and each
modification example are applicable to an ultrasonic apparatus
which performs ultrasonic therapy by transmitting an ultrasonic
wave to a subject.
A specific structure at the time of implementing the invention may
be configured by combining the respective embodiments and
modification examples with each other as appropriate within the
scope of being capable of achieving the object of the invention,
and may be altered to other structures as appropriate.
The entire disclosure of Japanese Patent Application No.
2017-000917 filed Jan. 6, 2017 is expressly incorporated by
reference herein.
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